Thursday, July 8, 2010

China Study Problems of Interpretation

The China study was an observational study that collected a massive amount of information about diet and health in 65 different rural regions of China. It's been popularized by Dr. T. Colin Campbell, who has argued that the study shows that plant foods are generally superior to animal foods for health, and even a small amount of animal food is harmful. Campbell's book has been at the center of the strict vegetarian (vegan) movement since its publication.

Richard from Free the Animal just passed on some information that many of you may find interesting. A woman named Denise Minger recently published a series of posts on the China study. She looked up the raw data and applied statistics to it. It's the most thorough review of the data I've seen so far. She raises some points about Campbell's interpretation of the data that are frankly disturbing. As I like to say, the problem is usually not in the data-- it's in the interpretation.

One of the things Minger points out is that wheat intake had a massive correlation with coronary heart disease-- one of the strongest correlations the investigators found. Is that because wheat causes CHD, or is it because wheat eating regions tend to be further North and thus have worse vitamin D status? I don't know, but it's an interesting observation nevertheless. Check out Denise Minger's posts... if you have the stamina:

The China study is an antithesis to some universal facts. I was surprised with the results - that grains are positively correlated to heart problems and that meat is showing no correlation at all. I don't know if how dietitians and nutritionistsdietitians and nutritionists in the US would react to that. That was just the China study anyway, a meta-analysis would soon be better.

The China study is an antithesis to some universal facts. I was surprised with the results - that grains are positively correlated to heart problems and that meat is showing no correlation at all. I don't know if how dietitians and nutritionistsdietitians and nutritionists in the US would react to that. That was just the China study anyway, a meta-analysis would soon be better.

I believe our intense over use of wheat has led to a lot of its problems... "Healing with Whole Foods" refers to wheat as assisting with weight gain more than any other food. Thanks for getting more info our their that this grain isn't always good for us!

I recall one of your posts on research suggesting wheatgerm intake increased utilisation of vitamin D stores, so perhaps the findings from Denise show this? High wheat intake in those living in northern latitudes leads to faster depletion of vitamin D and thereby impacts on CVD risk?

"Among the 8,000 statistically significant (at p<0.05) correlations we made, a few appear to remain at odds with the impressive ones noted above. For example, we found coronary artery disease to be associated with wheat flour intake (r = 0.67, p<0.001). Compared with populations that do not consume wheat flour, however, those that do also consume more milk (r = 0.27, p<0.05) and salt (r = 0.34, p<0.01), and have higher circulating levels of plasma triglycerides (r = 0.51, p<0.01), greater adult weight (r = 0.59, p<0.001), and less frequent consumption of green vegetables (r = 0.63, p<0.001). These factors may explain the association. Nevertheless, the wheat-flour effect appears to be independent of meat consumption, so enhancement of coronary artery disease risk by wheat consumption may be a possibility."

Nice to see you on the blog. Denise is going to do a separate post on wheat, so we'll see if the association holds up when other variables are controlled for (latitude etc). But I tend to agree with you that wheat is a problem.

We should bear in mind that the China Study is epidemiology writ large. One can't supplant double-blind placebo-controlled studies with dietary surveys. As in Renaissance Europe, meat consumption in China has long been associated with wealth. So perhaps the real message from the study is that it's better to be a well-fed omnivore, than a malnourished vegan. Thus even from an epidemiological standpoint what we really need is a group of rich Chinese who are voluntarily vegan, i.e. never lacking for micronutrients or calories, but foresaking animal foods. The other major problem that I see with the study is that there is a strong coreleation between genetic makeup and geography in China (certainly relative to the USA), so it could well be that what we're observing is people with good genes surviving despite an unhealthy diet, and vice-versa.

I think the only reliable takeaway is simply that processed food, and probably wheat, is garbage.

I do believe, based on better science elsewhere, that there is strong evidence for the existence of a healthy animal-based diet. But it's also possible to concoct a healthy vegan diet, superior to any in the China Study. I think the question of "best omnivorous diet" vs. "best vegan diet" is still unresolved.

Still, Minger's analysis is prodigious, and certainly presents us with a wealth of epidemiological evidence which suggests obvious targets for controlled experimentation. In this sense, her work (and Campbell's, for gathering all that data) is much appreciated by this reader.

I keep seeing this wealth objection and I'm not sure it's as relevant as might otherwise be.

I believe the data was collected in the early 80s, when China was still staunchly communist, i.e., pretty much everyone was dirt poor save, perhaps, a small group of elites but that shouldn't sway that much data.

I was in China in '86 and I saw nothing that suggested anything but a pretty egalitarian existence.

In the wheat argument it is important to keep in sight the difference between whole wheat naturally grown on mineral rich soils, properly processed for human consumption, and commercially processed and stored flour.

@Stanley: You say, "...it's also possible to concoct a healthy vegan diet..."

I'd be interested if you could elaborate. IMHO, "healthy vegan diet" is an oxymoron. Aside from Weston Price's work (he actively looked for a culture that ate a "healthy vegan diet" and was unable to find one), the only strictly vegetarian culture I'm aware of are the Jains of India. Even they consume animal products, in the form of dairy, to get the essential nutrients that, in a non-industrial setting, are only available from animal products.

If you're aware of a tradional, strict vegan culture, please do share.

When I said "wealth", I was referring to one's ability to procure sufficient nutrition and calories -- not property wealth. (Sorry I wasn't clear about this.) Certainly what you say about Chinese socioeconomics in the 1980s is true. But due to the very lack of transport infrastructure at the time, dietary wealth was very much determined by location. So those who lived near cows, for instance, could afford to consume much more dairy food than those who didn't. I really doubt that the vegan Chinese farmers were avoiding meat in order to stay healthy. They couldn't afford it, which is why I suspect that they also suffered from chronic malnutrition. Even caloric restriction can't compensate for bona fide malnutrition. So over a lifetime, we naturally observe that the animal product eaters maintained better health for longer.

Hi Robert,

After reading Stephan's damning wheat analyses, I'm no longer convinced that whole wheat is better than white bread, on account of its lectin content, which blinds the hypothalamus to leptin, if I recall. If you want to kill yourself and enjoy doing so, then whole wheat bread and cereal is a great way to go.

Hi Tuck,

While I do believe that a healthy vegan diet is possible, I don't know of anyone who follows one. My only point was that it could be constructed. I can't think of any nutrient that can't be supplied through vegan sources. I'm not saying that it's appetizing or cheap or easily assembled. Just that it's possible. You'd probably need to acquire some nutrients through supplements, but so what? Can you think of any nutrient that couldn't be obtained through nonanimal sources? Even DHA and EPA can now be produced by bacteria (if only they could get the carcinogenic hexane out of the end product, but that's a technological problem). And eventually, we'll debug vitromeat, at which point it should be more nutritious than the natural stuff (but probably won't be, since we'll tune it to taste like fast food).

@Stanley: Well, according to Dr. Campbell in "The China Study", vitamin B12 cannot be acquired from vegetable sources. B12 deficiency is widespread in vegetarian India. There are others that are extremely difficult to get adequate amounts of from vegetable sources, which include EPA and DHA. I've also heard (from Dr. John Briffa) that the vegetable sources of iron are not sufficiently bio-available to humans, that humans must get it from animal sources.

As an aside, the fact that the only nutritional deficiency of the vegan diet that Campbell mentioned in "The China Study" was B12 pretty much discredited the whole book for me. You cannot make his case honestly without discussing (or at least disclosing) the fact that a vegan diet is not satisfactory for human health.

I'll go out on a limb and say that it is impossible to construct a healthy vegan diet from traditional sources.

"The other major problem that I see with the study is that there is a strong coreleation between genetic makeup and geography in China (certainly relative to the USA), so it could well be that what we're observing is people with good genes surviving despite an unhealthy diet, and vice-versa."

91% of China's population is Han Chinese, and if you look at the map of areas where data was collected, you'll see that most were in Han majority areas. The monograph authors themselves dismissed genetic differences as insignificant.

"My own experience provides an example of a race, unsurpassed in perfection of physique and in freedom from disease in general, whose sole food consists to this day of grains, vegetables, and fruits, with a certain amount of milk and butter, and meat only on feast days. I refer to the people of the State of Hunza, situated in the extreme northernmost point of India. So limited is the land available for cultivation that they can keep little livestock other than goats, which browse on the hills, while the food supply is so restricted that the people, as a rule, do not keep dogs. They have, in addition to grains -- wheat, barley, and maize -- an abundant crop of apricots. These they dry in the sun and use very largely in their food.

Amongst these people the span of life is extraordinarily long; and such service as I was able to render them during some seven years spent in their midst was confined chiefly to the treatment of accidental lesions, the removal of senile cataract, plastic operations for granular eyelids, or the treatment of maladies wholly unconnected with food supply. Appendicitis, so common in Europe, was unknown. When the severe nature of the winter in that part of the Himalayas is considered, and the fact that their housing accommodation and conservancy arrangements are of the most primitive, it becomes obvious that the enforced restriction to the unsophisticated foodstuffs of nature is compatible with long life, continued vigour, and perfect physique."

I really doubt that the vegan Chinese farmers were avoiding meat in order to stay healthy. They couldn't afford it, which is why I suspect that they also suffered from chronic malnutrition."

First, there are no significant number of vegans. Nearly all Chinese eat at least some animal food. Second, Western Chinese ethnic groups that traditionally consume dairy like the Tuoli, Mongolians, or Tibetans are still very poor by even Chinese standards. They graze animals for milk and meat because rocky, arid lands aren't suitable for cultivation of grains or cabbage. I never much cared for rice, but Asians have long regarded refined white rice as a food of prosperity that, until modern times, was enjoyed only by the rich or during major celebrations just as white bread made from bleached white flour was considered a luxury when it was first introduced. That rural people lived mostly off locally or regionally produced foods is a strength of the data.

And regarding meat as food for the rich, meat eaten by Western Chinese ethnic groups isn't like the pulled pork or skinless chicken breasts we are so fond of. It is tough, grisley chunks that give the jaws a real workout. Likewise, the fermented milks consumed by Tibetans, Mongolians, and Uighurs are definitely an acquired taste very unlike our sweetened flavored yogurts.

The basic argument that the epidemiologist at your website made about Minger's data analysis was that it was oversimplified and not up to professional standards, but the whole point of Minger's analysis was simply to show how lacking and biased Campbell's own analysis was and that even an amateur analysis could tear it apart.

Instead of simply attacking Minger's analysis as oversimplified, why not ask the professional epidemiologist to look at Campbell's analysis and compare it to Minger's and see who did the better job?

Again, the main thing Minger is doing is saying that Campbell's analysis either sucks bigtime or he is just lying, but the epidemiologist does not say a single word in defense of Campbell.

The monograph itself states that it is only intended to be descriptive and does not aim towards identifying specific causes of diseases. The monograph states that more specific studies are needed for that. Campbell, of course, was one of the authors of the monograph.

I looked up that post (the link you provided seems to be down). I found it rather tiresome to be honest. She criticized Denise for using ecological data, but that's what the China study was. Anyone who analyzes the China study is using ecological data, so how is that a critique?

It would obviously be better to use multiple regression analysis on the data. According to what Denise said in the comments, she did that and it didn't change the overall results. Basically what she did was correct for the most obvious confounders, which accounted for the bulk of the confounding.

Here's what our anonymous internet epidemiologist would have to demonstrate to make her point:

1- Campbell relied entirely on data that were analyzed by multiple regression to come to his conclusions.

2- When analyzed by multiple regression, the data support Campbell's conclusion and not Denise's.

Until she can demonstrate that, this person is just flapping her lips. The ball is in her court if she wants to make a substantial contribution to the debate.

Iron: You're right about iron salt being much less available than hemoglobin iron. But you could always take more. If you choose the right iron source, then in principal you would not risk the bodily oxidation which would result from ingesting more bioavailable forms.

The simple fact is that it's already impossible to nourish the world with organic food, let alone real animal meat, because we have too many people and too little arable land. And if we're to venture off into space at some point, then the pigs and cows can't come with us. So despite the technological challenges, it's inevitable that humanity will become increasingly vegan.

Remember, "vegan" is really an ethical term -- not a dietary term. You can have a vegan who eats "beef" that was grown from stem cells. But historically, we've considered "vegan" to mean "plant and fungi eater" because we didn't have the technology to synthesize vitromeat and other "animal" products.

Yes, you're correct that most Chinese are Han. But I think you'll find that genetic differences correlate well with dietary differences. It seems to me that even in modern China, the people who eat more dairy tend to be more central Asians, e.g. Tibetans, with comparatively isolated gene pools. (The dating scene isn't exactly diverse at 14,000 feet!) I am of course open to being proven wrong. But in the meantime, I think that for this reason, the study has failed to test the effects of diet, independent of genetics.

You're also correct that China has "no significant number of vegans", especially considering the suppression of Buddhism during the 1980s. My point here was simply that the Chinese populations who, unlike the Touli and Tibetans, had no easy access to meat and dairy, were probably malnourished even from a strictly vegetarian perspective. And I doubt they could afford enough meat to really be considered omnivorous (heck, people died for lack of grain in Maoist times). So the study fails to compare an optimal plant diet with an optimal omnivorous diet.

I think what you've described from Hunza is a group of people who are sufficiently calorie-restricted to extend their lives, without being malnourished, in the face of a not-so-great diet. The cold temperatures would tend to reinforce this benefit. If they could afford to eat more of the same foods (especially the grains), then I suspect that they would tend toward dietbetes, like much of the urban Indian population, which is generally not living as close to starvation as these Hunza people. Still, it shows that can get away with such foods if you have iron will, or too little money. Interesting.

@Stanley, I said, "I'll go out on a limb and say that it is impossible to construct a healthy vegan diet from traditional sources."

Your latest comment confirms this.

"The simple fact is that it's already impossible to nourish the world with organic food, let alone real animal meat, because we have too many people and too little arable land. And if we're to venture off into space at some point, then the pigs and cows can't come with us. So despite the technological challenges, it's inevitable that humanity will become increasingly vegan."

Unfortunately you may be correct about this. Another term for this would be "starvation", since we also would be hard-pressed to industrially produce enough nutrients to feed a vegan world.

Stephan,I'm sure Denise Minger has done a good job, but some one has done her one better. On the Amazon comment section to the book The China Study, Richard Kroker, who says he is an egineer with a PHD has done a multiple variable regression analysis on the China Study raw data that is fascinating. Please check this out.

I'm familiar with this study from China, and the various interpretations. Face it, the guy is against eating any animal tissue, so it's a no brainer that his study would strongly support a vegan diet. I do have to say, this "Whole Health Source" blog is one of my favorites. Been reading it for a while, this is my first post.

While Chinese today mostly eat refined wheat products, rural Chinese on collectives ate very differently. I emailed a few Chinese professors of nutrition to ask about wheat consumption in the 70s and have gotten one response (it's morning now in China). Zhejiang University Professor of Nutrition Duo Li said in a brief reply that rural Chinese in the 70s ate whole wheat products and consumption of refined wheat flour was rare.

"My point here was simply that the Chinese populations who, unlike the Touli and Tibetans, had no easy access to meat and dairy, were probably malnourished even from a strictly vegetarian perspective. And I doubt they could afford enough meat to really be considered omnivorous (heck, people died for lack of grain in Maoist times). So the study fails to compare an optimal plant diet with an optimal omnivorous diet."

I'm confused here. Dairy and meat eating ethnic groups were also very poor, in fact, probably poorer than people in eastern villages. During the Cultural Revolution, easterners sent to western provinces were shocked at the extreme poverty and poor living conditions. Western provinces remain underdeveloped today. Nobody in China was eating an optimal diet back in the 70s. If poor meat eaters had better health than poor plant eaters, it's pretty hard not to hypothesize that at least some meat or dairy is necessary for health.

"But in the meantime, I think that for this reason, the study has failed to test the effects of diet, independent of genetics."

The authors of the monograph made very, very clear that the original study was intended to be descriptive, to provide data for forming hypotheses to be tested with specific studies. It didn't set out to prove or disprove causal links between diet and disease, so it didn't need to take genetic differences into account.

'I think what you've described from Hunza is a group of people who are sufficiently calorie-restricted to extend their lives, without being malnourished, in the face of a not-so-great diet.'

Calorie restriction simply means elimination of 'empty calories' from the diet. The same effect can be produced by periodic starvation, because this promotes autophagy, which breaks down damaged proteins. The Hunza would not have needed periodic starvation because they ate no empty calories.

Autophagy requires manganese. Wholemeal flour is high in manganese, and white flour is not.

What everybody at 30bananasaday.com doesn’t seem to realize is that there is no indication that Campbell himself used any of the analysis methodology that they insist Minger follow. That was the whole point of Minger’s analysis was to simply show that Campbell did not use proper statistical analysis.

That post about the proper way to analyze the data set applies to Campbell just as much as to Minger. You cannot hold Minger to a higher standard than Campbell. Campbell is actually the one who has a book out that many people look to for nutritional advice.

Campbell has had plenty of opportunity to make public the analysis that he did use, but so far he would rather talk about some Weston Price Foundation conspiracy against him instead.

If the people at 30bananasaday.com feel so strongly that proper statistical analysis must be performed, then they need to reject Campbell’s assertions on the China data outright because he has failed to even make his analysis methodology available. There is no way to document his compliance with the steps listed at 30bananasaday.com, so therefore he his in noncompliance and his assertions must be rejected. Unless he is God and not a scientist, then he gets a free pass…

If this person knows the right way to do the analysis, then why doesn't she do it?

This supposed epidemiologist over at your website is trying to intimidate Denise, without actually offering any substance to the debate herself. If this person is a scientist, I'd like to see her start acting like one.

If you want people to decide for themselves whether the Hunza story is 'fact or fantasy', you must give them the other side. If they read the article you gave, they should also read The Wheel Of Health by GT Wrench.

This book gives details of McCarrison's experiments on rats, which provided confirmation for the idea that Hunza health was due to their diet.

The authors of your article do not seem to have read this work, which was published in 1938 and should have been a primary source. Instead, they describe observations made in the 1950s, by which time Hunza health had declined due to contact with the West.

Certainly it is wise to read other sources about the Hunza. Perhaps the most accurate book is "Hunza: Lost Kingdom of the Himalayas" by John Clark (1957) as it was written by someone who actually lived there with the local people for some time. The book is out of print but is available online.

John Clark treated over 5000 patients during his 20 month stay, so he was familiar with the health of the Hunza.

Certainly the Hunza people had a lot going for them from a health standpoint. The young were breast fed for several years. The milk from goats, sheep and yaks was consumed raw. Some of the myths however, such as the claim that they only drank milk on feast days, make no sense. Did they throw away the milk the rest of the year?

Thanks for your reply. Yes, it's interesting how myths arise about the Hunza. Another myth is that they fermented their bread, which Clark and Wrench seem agreed they did not. Lots of people think unleavened wholemeal bread is an unhealthy food.

The same can be said for wheat, and of course for dairy products.To my mind, this is why the Hunza are so important. If their health really was as good as McCarrison says - and he was their doctor for 7 years - we have to ask whether a diet based on grains and milk might be just as 'paleo' as the standard paleo diet which excludes them. There is evidence that Neanderthals collected grain, which would support this idea.

I haven't read The China Study, but I rather think Campbell has misinterpreted what he found. Diets high in 'animal protein' often have a high iron-manganese ratio, a high zinc-copper ratio, and/or a high calcium-magnesium ratio. Iron, zinc and calcium overload, with corresponding deficiencies of manganese, copper and magnesium, are implicated in most or all degenerative diseases. Campbell will not be aware of this, because hardly anybody is. It's taken me 30 years to dig it out of the literature.

The Hunza diet would have excellent ratios of these metals, despite including quite a lot of 'animal protein'.

Mike Arnstein ran a 2:28 marathon this year at Boston. He is the FASTEST runner in the raw food movement today. Long time vegan and now powered by sweet fruit. How come there is no competitive athletes eating this 'paleo fat diet?' Please shut me up and show me cos Im sick of seeing cardio and muscle deficient paleo crew trying to debunk the china study that us elite athletes are thriving on.

"Gday crew,nice blog. Come and see if ANY of you guys can out bench press/dead lift/ ride/run us at

www.veganstrength.org"

Hmm, I dunno ...

"Andrew squatted 160kg, benched 97.5kg and deadlifted 212.5kg for a raw comp pb total of 470kg and the silver medal in the 90kg weight division.

Noah squatted 207.5kg, benched 180kg (in a bench shirt) and deadlifted 230kg for a comp pb total of 617.5kg and the silver medal in the 125kg weight division."

Should I really be impressed?

I squatted 170kg and deadlifted 205kg in the same competition in the 75kg weight class, my first competition after moving down from 82.5 weight class because of ... drum roll ... losing 7 kg on a paleo diet.

I have since squatted 185kg and deadlifted 210kg at the same 75kg bodyweight.

Harley Johnstone(Durianrider) is an endurance athlete! If he wanted to be a vegan body-builder he could - or so he says. Harley, I thought you had a very low B12 level when you were on "What's Good For You"? I saw a recent you tube where you were reporting an extremely high B12 level. Your cholesterol was high.

Oh, and while I'm at it, guys, let's be totally honest here - there were exactly two competitors in the 90kg weight division and exactly two competitors in the 125kg weight division. Feel free to throw a rotten egg at me when you see me at the future comps ...

Second, even if you don't care about health and just want to swim as fast as Phelps, I don't think copying his training program and diet will lead to good results. Most athletes experiment a lot before they find what works for them personally. And the real top athletes are usually genetically predespositioned to their sport. So copying Phelps' or Schwarzeneggers' training program may easily lead to overtraining or burnout.

And finally, there's not much sense in saying "Hey, try to outlift that vegan". Heaps of guys I know lift so much that my jaw drops, but not only they have never heard about paleo or raw veganism, but also their diets are full of stuff that's considered junk by overwhelming majority. But they may have been training for longer, training smarter, more persistently, harder, have different mentality, have started younger or their bodies may be better suited to lifting anatomically.

I did not notice any radical changes in my training when I started eating mostly paleo - diet is important, but to a certain extent only. Eating or not eating wheat or potato chips will most likely have long term effects, but, as Stephen mentioned, if raw veganism, or paleo, or any other diet gave a clear advantage, we would see high percentages of top athletes become followers.

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I'm a writer and science consultant with a background in neuroscience and obesity research. I have a BS in biochemistry and a PhD in neurobiology. I'm the author of "The Hungry Brain: Outsmarting the Instincts That Make Us Overeat".

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